The problem can be corrected by upgrading the affected package to version 2.6.8.1-16.20 (for Ubuntu 4.10) and 2.6.10-34.3 (for Ubuntu 5.04). You need to reboot your computer after doing a standard system upgrade to effect the necessary changes.

Details follow:

A Denial of Service vulnerability has been discovered in the ptrace() call on the amd64 platform. By calling ptrace() with specially crafted ("non-canonical") addresses, a local attacker could cause the kernel to crash. This only affects the amd64 platform. (CAN-2005-1762)

ZouNanHai discovered that a local user could hang the kernel by invoking syscall() with specially crafted arguments. This only affects the amd64 platform when running in the 32 bit compatibility mode. (CAN-2005-1765)